The results indicate that the STRAIGHT vocoder has the most Gaussian parameter distributions and most robust synthesis quality, whereas the GlottHMM vocoder has the most emotion sensitive parameters and best but unreliable synthesis quality. The HSM vocoder's LSF parameters were found to be more Gaussian than the GlottHMM vocoder's LSF parameters. HSM was found to be sensitive to noise, and it scored the lowest score on the subjective listening test.